A comparison of antibodies to TRIC agents in serum and tears of infected persons will be carried out on specimens collected during repeated examinations in Tunis, in an effort to relate titers to clinical activity and to courses of treatment. The sera and tears of naturally or experimentally infected persons will be absorbed with antigens of TRIC groups A to F and the immunologic pattern of residual antibodies will be established quantitatively. This may indicate to what extent the first infection with a TRIC agent fixes the pattern of immunologic response, including antibody and delayed type hypersensitivity. As a result of repeated, controlled trials of chemotherapy for active trachoma in students at Indian Boarding Schools, certain individuals have been identified who have many, repeated episodes of disease activity in spite of drug administration. An effort will be made to identify possible reasons for this failure to respond, including unusually heavy exposure to a TRIC agent shedder in the immediate environment and an abnormality in immunologic response which may distinguish these individuals from their cohorts who do not exhibit this marked tendency to relapse of trachoma activity. Herpesviruses will be isolated from women who had lesions late in pregnancy, and their offspring will be followed for clinical and serologic evidence of herpesvirus infection of resistance. The frequency of herpesvirus type 2 in keratoconjunctivitis will be estimated.